The present invention relates to hydraulically controlled brake systems for motor vehicles, comprising a master cylinder, a corrector intended for reducing the pressure prevailing in the rear-wheel brakes in relation to that prevailing in the front-wheel brakes, and a wheel anti-lock device.
Such systems are known to an average person skilled in the art. The document FR-B-2,550,747 describes, for example, such a system in which the corrector is inactivated when the wheel anti-lock device comes into operation and takes over the control of the brake circuit. However, this inactivation of the corrector is accompanied by an abrupt increase of pressure in the rear-wheel brakes before the anti-lock device can act correctly. This abrupt increase is utterly detrimental to braking under good conditions of safety and comfort.
To overcome this problem, the document FR-A-2,624,462 proposes normally to short-circuit the corrector as soon as the vehicle so equipped is moving, a maximum pressure being applied to the rear-wheel brakes and being modulated by the anti-lock device, and to activate the corrector only in the event of a failure of the anti-lock device.
The document FR-A-2,571,326 provides an alternative version of this solution, according to which the corrector is inhibited completely during normal operation. However, this simply means that the anti-lock device is operated very frequently as soon as the vehicle has to brake. Now an anti-lock device is a fragile element, the lifetime of which is reduced by over-frequent operation, its components being subjected to premature wear.